In simple terms, an ID project has two parts: enrollment and verification.
Enrollment is the process by which a user is vetted by, entered into, or purchases an ID management regime.
Verification is when the ID management solution actually has to fulfill its intended function.
You don't really know for certain if the key you just had made is going to open your front door until you try it. You won't know if the combination lock you just bought works until you try it. And India won't know how smoothly the UID-based system can provide a transition away from the subsidy system to the cash transfer system until it gives it a try.
Verification is where the rubber meets the road and India is about to take its first UID test drive as Dr Manmohan Singh, Prime Minister of India, announced last month the launch of a direct electronic cash transfer scheme leveraging India’s Unique Identification (UID) Programme. (FutureGov)
The government has announced that direct cash transfer of subsidies to the bank accounts of the recipients would start in 51 out of India’s 659 districts from January 2013 and would be gradually extended to the rest of the country by April 2014. (The Hindu)
Hopefully things go well. It's hard to overstate the challenge involved or the importance of the project's success.